1. Field of the Invention
The present invention relates to a high-frequency circuit module such as an oscillator, filter, duplexer, etc., to be used in microwave bands and millimeter wave bands, and a communication device using the module.
2. Description of the Related Art
The inventor disclosed in Japanese Unexamined Patent Application Publication No. 8-265015 that by providing electrodes having electrodeless portions opposing each other on both surfaces of a dielectric substrate, a TE010 mode resonator can be formed in an area sandwiched between the two electrodeless portions and its vicinity in the dielectric substrate.
Furthermore, in Program C2-68 in the IEICE Electronics Society Conference (September, 1997), Japanese Unexamined Patent Application Publication No. 11-214908, and Japanese Unexamined Patent Application Publication No. 10-145117, a high-frequency circuit module such as a filter, oscillator, etc., using the above TE010 mode resonator is disclosed.
In the high-frequency circuit module using the above-mentioned conventional TE010 mode resonator, by stacking a resonator substrate constituting the TE010 mode resonator on a front side of a circuit substrate having lines formed thereon or on the back side of the circuit substrate, the lines on the circuit substrate are coupled to the above-mentioned resonator.
However, when a resonator substrate constituting a resonator is mounted on the back side of a circuit substrate, the electrodes on the resonator substrate may be placed in contact with the grounding electrode on the circuit substrate by a leaf spring and they may be joined using a conductive adhesive. In such a case, it has been feared that the contacting condition between the electrodes may change because of temperature variations and changes with time, the coupling between lines on the circuit substrate and the resonator may become unstable, and the characteristics may thereby be changed.
Furthermore, in the construction in which the above resonator substrate is mounted on a circuit substrate, it may be required to arrange the substrates separated by a spacer so that the electrodes on the back side of the resonator substrate may not come into contact with the lines on the circuit substrate, etc.
Now, the degree of coupling of a resonator provided on the above resonator substrate with a line on the circuit substrate is proportional to a magnitude of magnetic flux of a resonance mode at the location of the line on the circuit substrate. But because much of the resonance energy of the resonator is confined inside the resonator substrate, it is difficult to obtain a high degree of coupling to the line on the circuit substrate, existing outside the resonator substrate. Furthermore, in order to increase the degree of coupling, the line on the circuit substrate may be arranged so as to be closer to the middle of the resonator, but because of that, it is feared that the electromagnetic field of the resonance mode may be disturbed, the Q value may be degraded, and an unwanted resonance mode may be induced.
In view of the foregoing problems, the present invention provides a high-frequency circuit module in which a degree of coupling of a line to a resonator composed of a dielectric layer sandwiched between electrode layers can be easily increased, reliability is improved, a spacer, etc., is made unnecessary, and a high Q value is obtained so that unwanted modes are not generated.
The invention further provides an oscillator, a filter, and a duplexer, and a communication device using them, by utilizing the construction of the above high-frequency circuit module.
In a high-frequency circuit module according to an embodiment of the present invention, electrodeless portions opposing each other are provided in two electrode layers with a dielectric layer sandwiched therebetween, at least one intermediate electrode layer is provided between the two electrode layers, and an electric line coupled to a resonance mode generated in an area sandwiched between the two electrodeless portions and its vicinity is formed in the intermediate electrode layer.
Because of this construction, a resonance mode generated in a resonance area sandwiched between the electrodeless portions opposing each other and the line in the intermediate electrode layer are coupled. As the line is inside the resonance area where a strong resonance energy is confined, a high degree of coupling can be realized.
Furthermore, in a high-frequency circuit module according to an embodiment of the present invention, part of the intermediate electrode layer may be exposed and, for example, mounting parts to be electrically connected to the above line may be disposed on the module. Because of this construction, mounting parts can be easily mounted and connected to a line coupled to the above resonator constructed in an area sandwiched between electrodeless portions opposing each other.
Furthermore, in a high-frequency circuit module according to an embodiment of the present invention, at least one of the two electrode layers may be provided with an electrode connected to electrodes in the intermediate electrode layer and mounting parts may be disposed on the electrode. Because of this construction, without requiring any particular processing of a multilayer substrate containing a plurality of dielectric layers, mounting parts can be mounted on one side of a substrate and accordinglyproductivity can be improved.
Furthermore, in a high-frequency circuit module according to an embodiment of the present invention, a through-hole may connect at least the two electrode layers formed in the dielectric layer. In this way, the through-hole portion inside the dielectric layer is at the same electric potential as the two electrode layers which are at the ground electric potential, and spurious modes such as parallel-plate modes being propagated between the above electrode layers, etc., are suppressed.
Furthermore, in a high-frequency circuit module according to an embodiment of the present invention, the lateral width of the two dielectric layers sandwiched between the two electrode layers and the intermediate electrode layer can be made different from each other. Because of this construction, as the resonator in the area in which the above two electrode layers oppose each other is provided only in the resonance area sandwiched between the two electrode layers, the frequency of spurious modes such as parallel-plate modes, etc., can be shifted to a higher-frequency region where the spurious modes are practically insignificant. Furthermore, because the width of the dielectric layer sandwiched between one electrode layer of the two electrode layers and the intermediate electrode layer has become narrower, the arrangement of electrode patterns and mounting parts on the exposed surface of the other dielectric layer becomes easier, and accordingly higher performance and more mutifunctional products become possible. Furthermore, the adjustment of electrode patterns on the exposed surface by trimming also becomes easier. Moreover, as the amount of dielectric material can be minimized, weight and cost can be reduced.
In an oscillator of the present invention, a reflector amplifier is connected to the electric line in the above high-frequency circuit module.
In a filter of the present invention, part of the electric line in the above high-frequency circuit module is led out as an input-output terminal or an electrode coupled to such an electric line is led outside as an input-output terminal.
In a duplexer of the present invention, a plurality of the resonance areas are provided, and an electric line coupled to resonance modes in two resonance areas is led outside as a common input-output terminal or an electrode coupled to such an electric line is led outside as a common input-output terminal.
In a communication device of the present invention, the above filter or duplexer is used, for example, as a signal processing part or as an antenna sharing unit for conducting a transmission signal or reception signal in a high-frequency circuit.
Other features and advantages of the present invention will become apparent from the following description of embodiments of the invention which refers to the accompanying drawings, in which like references denote like elements and parts.